The present invention relates generally to workpiece cutting machines and especially to table saws. More particularly, the present invention relates to various anti-kickback apparatuses, dust-deflecting features, machine carrying features, and apparatuses for supporting and handling large workpieces.
A typical cutting machine or table saw generally includes a base that supports a generally flat table top having a longitudinally extending throat slot or opening through which a saw blade or other cutting tool protrudes above the table for engaging a workpiece. A motor is mounted beneath the table top, and the cutting tool, typically a circular saw blade, is mounted for rotation with the output shaft of the motor. The blade or cutting tool is positioned to effect cutting of the workpiece as it is moved longitudinally along the table in a frontward-to-rearward direction generally parallel to the plane of the cutting tool. The blade or other cutting tool can be lowered or raised with respect to the table top to accommodate workpieces of varying thicknesses and can be adjusted to various angular orientations relative to the plane of the table top in order to cut bevels or other such angular cuts on the workpiece. Typically, a kerf splitter or riving knife is adjustably raised or lowered and/or disposed at various angular orientations along with the blade or cutting tool.
Power driven cutting devices, such as table saws, planers, jointers and the like, have frequently been cumbersome and difficult to transport from one work site to another. Or, if made to be readily transportable, such devices have typically been ill-suited for performing cutting operations on large workpieces.
In addition, such prior cutting machines have recently begun to be more frequently equipped with built-in dust or chip extraction apparatuses, but many of these extraction apparatuses still fall short in their ability to effectively convey dust and chips away from the cutting site and to avoid undesirable accumulation of dust or chips inside cabinets or enclosures housing the various drive assemblies and cutter positioning mechanisms of the cutting machine.
Furthermore, the prior art guard mechanisms on such cutting machines have frequently included anti-kickback devices designed to prevent the rotating blade or other cutting tool from grabbing fully or partially cut workpieces and dangerously throwing rearwardly, back toward the operator. A typical example of such anti-kickback devices includes downwardly-biased spring-loaded pivotable anti-kickback pawls spaced apart on opposite sides of the kerf splitter or riving knife, which is positioned rearwardly of the blade or cutting tool and aligned with the cutting plane. Such pawls commonly include toothed or serrated lower edges under which the workpiece slides as it is fed rearwardly past the blade, but which grip the workpiece and prevent it from being kicked back if it tends to move back toward the operator. However, such prior anti-kickback pawls are frequently easily deflected laterally toward the blade or cutting tool, where they can become caught between the splitter and the slot in the saw's throat plate or between the splitter and the edge of a workpiece and thus become rendered ineffective. Additionally, it has been found that the serrated lower edges of such anti-kickback pawls tend to undesirably dig into or abrade the softer metal or plastic material of the throat plate, such as when the blade is raised and then lowered.
In table saws or other cutting machines with the work table having a downwardly-extending flanged edge extending around at least a portion of its periphery, the present invention provides one or more carrying members on an underside of the work table generally adjacent the flanged edge. Such carrying members have a lateral dimension substantially greater than the lateral thickness of the flanged edge in order to provide an increased gripping surface area to be grasped by the operator in order to lift and transport the cutting machine from one work location to another. Such carrying members can be separate and attached to the underside of the table or integrally formed with the table. Such cutting members can be defined by a series of spaced-apart ribs extending downwardly from the underside of the work table and located generally adjacent the flanged edge thereof. In this embodiment, the ribs have downwardly-facing edges that together define the increased gripping surface area.
The table saw or other cutting machines in accordance with the invention are preferably equipped with one or more extension support assemblies for supporting a workpiece extending horizontally outward of the lateral extent of the work table. Such extension support assemblies can be provided at the front (infeed) and/or rear (outfeed) sides of the work table and/or on either or both of the right and left sides. These extension support assemblies include generally horizontal support members and at least one rod or other such extension member slidably extendable horizontally from beneath the work table in directions toward and away from the work table, with the support members being interconnected with the rod for slidable extension toward and away from the work table with the rod.
In this regard, it has been found to be especially advantageous to provide such an extension support assembly on the left side of the work table (as viewed by an operator standing at the front side of the work table). This arrangement, according to the invention, can be combined with a rip or other workpiece feed fence that is capable of being positioned on only the right side of the blade or cutting tool, or with a fence positionable on either the right or the left side of the blade or cutting tool. In such an arrangement the left-side extension support member can be extended leftwardly out to a distance from the work table sufficient to support a common four-foot wide by eight-foot long sheet material workpiece (such as a plywood or particle board sheet or other common four-by-eight sheet materials) on the left side of the blade at or leftwardly beyond the longitudinal centerline of the sheet as it is fed longitudinally into the blade or cutter with its long dimension parallel to the plane of rotation of the blade or cutting tool and with the fence on the right side of the blade or cutter, regardless of how close to the blade or cutter the fence is positioned. Therefore, in such a setup, a four-by-eight sheet workpiece can have a greater amount of its weight supported by the work table and the left-side extension support assembly than the amount of its weight that is leftwardly beyond the extension support member and unsupported, no matter how much of the sheet is being rip-cut off between the right side of the blade and the rightwardly-positioned rip fence. Thus, because the center of gravity of the four-by-eight sheet is always inboard (toward the blade or table) of the leftwardly-extended support member, the operator can more easily maneuver and control such four-by-eight sheet workpieces during longitudinal ripping operations. This arrangement can also be employed in a right-side extension support assembly for rip-cuts made with the fence on the left side of the blade.
Preferably, in at least some forms of the invention, such support members are removably interconnectable with the rod or rods in either of a first or a second reversed or inverted orientation. The upper surfaces of these support members are coplanar with the upper surface of the work table when said support members are in the first orientation in order to support the workpiece flatly extending across the upper surface of the work table and across said upper surface of said support member. However, the upper surfaces of the support members lie in a lower plane, beneath the plane of the upper surface of the work table, when the support members are in the second inverted orientation. In this embodiment, the work table has a second upper table ledge surface adjacent its peripheral edge and coplanar with the lower plane. This allows an auxiliary work support panel adapted to be removably placed upon and supported by the second upper table ledge surface and the upper surface of the support members when in the second inverted orientation.
In addition, the present invention also provides for greater ease of slidably moving the support members inwardly and outwardly, toward and away from the table. This advantage is accomplished by providing one or more brackets under the work table with openings in such brackets for slidably receiving the rod or rods (or other such slidable extension members) and with such openings in at least the outboard of such brackets being enlarged horizontally to afford greater clearance when the rods are deployed inwardly or outwardly. For example, in one preferred embodiment having one or more cylindrical rods, the brackets support openings are somewhat elliptical in shape, with the major axis being oriented horizontally such that greater rod clearance is provided laterally or horizontally than vertically. This substantially eliminates, or at least minimizes, any tendency of the rod to bind during slidable movement, especially if the extension support assembly is not moved inwardly or outwardly in a direction perfectly perpendicular to the side of the work table. Furthermore, such horizontally-elliptical bracket support openings tend to self-center the rods, thus further contributing to their smooth, sliding movement.
Preferably, according to the present invention, the work table also includes a dust deflection skirt extending generally downwardly from a lower surface of the work table at least partially vertically into the generally hollow dust-receiving cavity portion of a dust shroud located within the saw's enclosed base and generally surrounding the lower portion of the blade. This skirt serves to deflect dust or chips produced by the cutting of the workpiece generally inwardly into the interior of the hollow dust-receiving cavity, especially when employed in conjunction with blade/splitter assemblies that can be raised or lowered, and/or angled, such that the blade or cutter directs such dust or chips toward different areas of the dust receiving cavity at different heights and/or angles.
Also, the preferred forms of the invention offer an improvement to the conventional table saws having a kerf splitter plate generally aligned with the cutting plane of the cutter and a pair of anti-kickback pawl pivotally attached at a generally upper end thereof to opposite sides of the kerf splitter plate and spaced laterally therefrom to slidingly engage its lower edge with the workpiece as it is moved past the cutter. The invention provides a generally button-shaped anti-kickback spacer attached to the anti-kickback pawl at an intermediate location thereon between the pivotal attachment to the kerf splitter plate and the lower edge of the anti-kickback pawl. Such spacers slidably engage the kerf splitter plate during pivoting of the anti-kickback pawl and are of thicknesses adapted to maintain the anti-kickback pawl in a generally parallel relationship with the kerf splitter plate. According to the invention, such spacers can be composed of, or coated with, a low-friction synthetic material and can either have a split root attachment portion with barbed ends to allow them to be easily and conveniently snapped into place in mounting holes on the pawls or be of a sealed-end blind rivet construction for ease of mounting on the pawls.
Additionally, the present invention provides hardened portions of the throat plate under the anti-kickback pawls to prevent them from gouging or digging into the softer material of the remainder of the throat plate when the blade and splitter are raised, lowered or angled with respect to the table top plane and to prevent the blade/splitter height and angular adjustment mechanism from binding when such height and angle adjustments are performed.
Additional objects, advantages, and features of the present invention will become apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings.